Filtering device for coffee makers



Dec. 11, 1951 M. s. ZISKlN ETAL ,9

FILTERING DEVICE FOR CQFFEE MAKERS Filed Jan. 17, 1948 I um FIG. 2

-]NVENTORS. MANUEL S. ZlSKlN LESTER W CLINE ATTORNEY .means for filtering the brew.

Qur invention is particularly adapted to be- Patented Dec. 11, 1951 "UNITED Miss earner FILTERING DEVICE FOR COFFEE MAKER-S Manuel -8. Ziskin, University Heights, and Lester .Oline, :Berea, Ohio, assignors. .to 'zKromcx Corporation,..Cleveland, Ohio, a corporation of Ohio ApplicationJanuary 17, 1948,i'SerialiNo.-2;8 93

.1Claim. ;1 This invention .relatesgenerally-to coffee brew- .ing devices and more particularly .to improved usedin conjunction'with the type ofcofieemaker in which water is elevated under pressure from -awatercompartment into a brewing vessel which contains .the coffee grounds.

After the .brew has been prepared, the pressure is permitted to subside and 17118 :brew flows .backintothe water compartment.

.It is desirable .that -.the brew be clear, that is, free from=coifee grounds, and to attain this objective, various sorts of filters have been devised, including :wire, cloth-and paper mesh filters, to strain the brew as it returns .to the water com- .partment.

it is .a .primaryaobjectof our invention to provide .a. filtering device which will efficiently strain the brew and keep it free of coffee grounds.

Another object of our invention is to provide a filtering device of the character described,

which does .not require periodic replacement,

.thereby avoiding the expense which is associated with the useof expendable types of filters.

Still anotherobject .of our invention is to provide a filtering-device which Will not clog during the performanceof its function, and will, therefore, .permit the relatively rapid .return of the coffee brew :to the water compartment.

:A further object of .our invention .is :to .provide afiltering device which may be'easilyandlquickly cleaned :after use.

:Otherobjects and advantages of our invention will become apparent during :the course of the following description.

In the annexed drawings, forming :a part of this specification, and in which like numerals are employed .to designate like parts throughout the same,

,Fig. .1 is a cross-sectionalview of .acofiee maker embodying the filter which is the subject of our invention, the filter .being shown .in elevation.

(CLIZIO-JBZ) lower portion of the .vessel2 islcupped toiorme central well 3 having a bottom wall 4 from which depends, centrally thereoia tube .5, which extends into the Water compartment I and termi- ,nates a slight Qdistance :above the bottomsofithe compartment.

The compartment i has a central opening 1 which is definedby a necked portion 8 at the top of the compartment. The opening I is-adapted to be sealed by a rubber gasket 9 which is'moun-t- .ed circumferentially on theexterior of the vessel 2.

In utilizing .a coffee-making device of the type above mentioned, it is customary to fill the .com-

ipartznent .1 with .watenand to .place'inwthe vessel .2 the .cofiee grounds.

As the end of the tube :5 is submerged in the water, the vapor pressure .of

the water will force the water to ,pass upwardly through the tube -5 and into the vessel .2, when the water is heated. The ,Water will mix with the coffee grounds in the vessel :2 and form the hrew, after which the coffee maker is removed from the .heatand the brew :flows aback-into th compartment .1.

It will :be apparent that, in order to prevent thecoitee grounds from being present in the brew when it :isready .to be served,.it is necessary that .a-straining or .filtering device be interposed .be-

tween the compartments 1 and the vessel .2 and .for this purpose, we utilizeour novel filter, desig- .nated generally by the numeral H].

The filter It! comprises four parts, a .sealing disc@l;i,.a-spacer.dis.c i:2,.a stem [3 and astabilizer rod M. As .best .seen in Fig. 3, the sealing disc H is in the formof a. flat circular disc provided with a-central opening 15 and .a plurality of circumferentially-spaced openings L6.

The spacer .disc I2 .is also a flat .circular disc of the samesize as the sealing .disc .Li and itis .provided with a centrally located .opening .I'I. Surrounding the opening H is an annular embossment l8 and a series of circumferentiallyspaced embossments [9, the embossments i8 and l 9 forming projections on the surface .of the disc 12, the (purpose of which will be hereinafter-described.

The discs I l and 42 .are adapted .to he loosely mounted on the cylindrical .stem stem L3 which terminates in an extension .20 of reduced diameter, therebyiorming the shoulder .Zl. The 'diameter of the openings .95 and .Il is .smaller'than the diameter .of the stem 13, although the diameterof the extensionIZD is such that the discs Li .and 1.2 are readily slidable thereon.

The end oirthe extension 201s taperedslightly 3 in order to permit the extension to be wedged into a cavity 22 which is centrally located in one end of the stabilizer rod I4.

As seen in Fig. 2, the filter I is placed in the vessel 2 in such a manner that the stabilizer rod I4 extends downwardly within the tube 5 and the sealing disc I I rests on the bottom 4 of the well 3. The spacer disc I2 rests on top of the sealing disc I I, being maintained in spaced relationship thereto, however, by the projecting embossments I8 and I9. The weight of the stabilizer I4 maintains the stem I3 in abutment against the spacer disc I2, the shoulder 2I acting to limit the downward movement of both the stabilizer II and the stem I3.

It will be noted that the spaced relationship or the discs II and I2 permits a passageway or gap 23 to be formed between the adjacent surfaces of the discs II and I2 and it is well to mention at this point that the distance between the two discs,

which defines the gap 23, is critical and must be accurately maintained. In the embodiment shown, the embossments are so formed as to project not less than .006 inch and not more than .0075 inch, the gap thus defined being sufilciently narrow to prevent the passage therethrough of coffee grounds and yet being sufficiently wide to permit the relatively rapid flow therethrough of the liquid brew as it passes from the vessel 2 to the compartment I.

The description of the operation of the coffee maker, previously given, may now be modified to include the functioning of the filter I0. When the filter I0 is in the position shown in Figs. 1 and 2, the abutment of the sealing disc I I against the bottom of the well 3 prevents the dry coffee grounds from falling into the water compartment I. When the heated water is elevated from the compartment I it passes readily through the opening I6 in the disc I I and through the gap 23 between the discs II and I2, into the vessel 2. Water will continue to flow into the vessel 2 until the level of the water in the compartment I falls below the end of the tube 5. Continued heating of the water will cause steam to bubble up through the tube 5 and into the coffee mixture in the vessel 2, thereby agitating the mixture so that the full flavor may be extracted from the coffee grounds.

As the boiling increases in vigor, the steam generated will increase in volume thereby intermittently displacing the spacer disc I2, which is free to move relatively to the sealing disc I I. In order to prevent the steam pressure in the compartment I from becoming unduly great, the filter III must be sufiiciently light in weight to be displaced at low steam pressures, and yet heavy enough to permit the steam pressure to build up to .a point where vigorous agitation of the brew will be effected. In the embodiment of the present invention, the filter ID has been found to function most satisfactory when its weight, exclusive of the sealing disc II, is approximately 2 /2 ounces.

When the spacer disc I2 is displaced by the steam pressure as seen, somewhat exaggerated for purposes of clarity, in dotted outline in Fig. 2, the width of the gap 23 is considerably increased. However, the velocity and pressure of the escaping steam will prevent any counter-flow of coffee grounds into the gap 23.

After the coffee has been brewed for a sumcient length of time, the heating is discontinued. As the compartment I cools, the steam therein condenses creating a slight vacuum; The differ- 4 ential in pressure thus created between the compartment I and' the vessel 2 causes the brew to flow back through the gap 23, the openings II, and the tube 5, into the compartment I, from which it may be served.

During this fiow back of the brew, the leached coffee grounds are prevented from passing Into the compartment I by the discs II and I2, the gap 23 being of such narrow width as to effectively obstruct their passage, while, at the same time. permitting a relatively rapid flow of the liquid.

In using the common type of cloth or paper mesh filter, the coffee grounds collect on the surface of the filter and form a thick layer of pastelike consistency which clogs the filter openings and obstructs the passage downwardly of the fluid through the filter. The formation of this barrier is in large part due to the fact that the filtering surfaces are disposed in substantially horizontal planes on which the coffee grounds would naturally settle. In contrast thereto, it will be manifest that the gap 23 of the filter II) provides a channel which is disposed at right angles to the natural flow pattern of the liquid. The coffee grounds settle predominantly on the horizontal surface of the spacer disc I2, which surface plays no part in the filtering process. Thereby, the entrance to the gap 23, which is the filtering medium, is less likely to be obstructed or clogged by the coffee grounds, and the liquid fiows rapidly into thelower compartment I. D

It will be noted that the filter III is readily removed from the vessel 2, it being maintained in position by its own weight only, as contrasted to other types of filters which are wedged into place or otherwise frictionally held. After it is removed, the filter III may be easily and quickly cleaned by rinsing with water, there being no disassembly of the parts required and no clogging of the mesh, as is customary in other types of filters.

It will be thus apparent that we have provided an efficient filtering device for coffee makers which requires no periodic replacement, which is not subject to the wear and tear of frictionallyheld devices, which is easily cleaned after use, and which is so constructed as to minimize the clogging effect of the coffee grounds.

It is to be understood that the form of our inventicn herein shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of the parts may be resorted to without departing from the spirit of our invention or, the scope of the subjoined claim.

Having thus described our invention, we claim:

A filtering device for a coffee maker of the type having an elevated brewing vessel opening into a lower receptacle, said filtering device comprising a flat thin metal disk having a plurality of openings therein, said disk being adapted to overlie the opening between said vessel and said receptacle, a second thin metal disk superimposed on said first-named disk in axial alignment therewith, projections formed on one of said disks and abutting the surface of the other of said disks to retain said disks in axially spaced relationship, said projections being disposed inwardly of the periphery of said disks but outwardly of the openings in the first disk whereby the conjoint edges of said disks define an uninterrupted horizontal annular fiow channel, said channel being of such dimension as to restrain the passage therethrough of coffee grounds, a stem having a portion of reduced diameter extending through said disks and providing a shoulder which rests on the second disk, said reduced portion extending into said lower receptacle to maintain said disks in axial alignment, and a removable stabilizing rod of predetermined weight frictionally secured to said stem extension and extending freely into said lower receptacle to yieldably maintain said stem in vertical position, the axial distance between said stabilizing rod and said stem being greater than the thickness of said disks in combination.

MANUEL S. ZISKIN.

LESTER W. CLINE.

' REFERENCES CITED The following references are of record in the file of this patent:

6 UNITED STATES PATENTS Number Name Date 1,926,557 Perkins Sept. 12, 1933 1,992,101 Stuart Feb. 19, 1935 2,027,826 Keaton Jan. 14, 1936 2,042,537 Liddell June 2, 1936 2,969,939 Browning Feb. 9, 1937 2,234,678 Matson Mar. 11, 1941 2,289,498 Hons July 14, 1942 2,386,433 Carter et a1. Oct. 9, 1945 2,387,322 Francis 1; Oct. 23, 1945 2,390,269 Peterson Dec. 4, 1945 2,495,996 Wolcott Jan. 31, 1950 

